Lack of macronutrients such as protein or micronutrients such as pyridoxine, especially during the vulnerable period of development, inhibits skeletal and brain development. Pyridoxine (Vit. B6) is associated with the formation of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter substance. Though biochemical, electrophysiological and behavioral studies have indicated changes due to pyridoxine deficiency, there exists a significant lack of morphological data in pyridoxine-deficient states. The objectives of the research proposal are three-fold. The first is to establish the histological and cytological features of postnatal development and maturation in the Purkinje cell and the pyramidal cell of layer V of frontal cortex of rat in: 1) pyridoxine-deficient pups; 2) pyridoxine-deficient pups administered daily subcutaneous injections of B6 throughout the experiment; 3) pyridoxine-deficient pups supplemented with subcutaneous injections of B6 during 4-6 postnatal weeks; 4) pups fed pyridoxine-supplemented diet; 5) pups fed restricted amount of pyridoxine-supplemented diet constituting the weight-matched malnourished rats; and 6) pups fed normal rat chow. These studies will be conducted on semithin (0.5 micron) plastic embedded sections at the light microscope level, and on thin sections using the electron microscope. The size of the Purkinje cell and pyramidal cell will be established using the light microscope. The second objective is to a) quantitate the vascular density of the developing cerebellum and frontal cortex using semithin sections; and b) establish the cytology of the developing capillaries using the electron microscope. The third objective is to study the pattern of dendritic tree arborization of the Purkinje cell and the pyramidal cell of layer V of frontal cortex using the Golgi impregnation technique.